The World's 18 Strangest Dams

Whether its builder is a beaver or a person, a dam is always used for the same purpose: to manage, direct and prevent water flow. Within that definition, there are many different types of dams, from mammoth hydroelectric generators—which produce 20 percent of the worlds' electricity energy and 88 percent of all renewable electricity—to the small sand dams of Kenya that are designed to store water for the dry season. There an estimated 845,000 dams in the world; here are our picks for the 18 strangest.

Three Gorges Dam

Three Gorges Dam

Where: Sandouping, China–Yangtze River

Why It's Unique: China's Three Gorges Dam is not only the world's largest hydroelectric dam, it's also the world's single largest source of electricity. The construction of the dam has been convoluted: Preliminary plans began as far back at 1932 but construction but didn't start until late 1994; the dam isn't scheduled to be completely finished until 2011. The structure's estimated life is as short as 70 years; that was deemed long enough to justify the displacement of 1.24 million people.

Itaipu Dam

Itaipu Dam

Where: On the border of Brazil and Paraguay–Parana River

Why It's Unique: The Itaipu Dam, a partnership between Brazil and Paraguay, generated over 90,000 gigawatt hours of power in 2000—then a world record for hydroelectric generation. With a height of more than 196 meters, the dam stands as tall as a 65-story building. Its construction used enough steel to build 380 Eiffel Towers, along with 12.3 million cubic meters of concrete.